<!DOCTYPE html>
<link rel="help" href="https://drafts.csswg.org/css-scroll-anchoring/">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
    body {
        height: 5000px;
    }

    .filler {
        width: 20px;
        height: 500px;
        background-color: silver;
    }

    #container {
        height: 800px;
        width: 800px;
        padding: 10px;
        border: 1px solid black;
    }

    #target {
        border: 1px solid gray;
        padding: 10px;
        height: 150px;
        background-color: orange;
    }
</style>

<div id="container">
    <test-container id="shadowHost" >
        <div class="filler">
        </div>
        <div id="target">
            <p>Scrolling over this element doesn't scroll the main scroller<p>
        </div>
        <div class="filler">
        </div>
    </test-container>
</div>

<script type="module">
    const content = document.getElementById('target');
    class TestContainer extends HTMLElement {
        connectedCallback() {
            const shadow = this.attachShadow({ mode: 'open' });
            shadow.innerHTML = `
                    <div id = "shadowScroller" style="height: calc(100% - 20px); overflow: auto; border: 1px solid green; padding: 10px">
                        <slot></slot>
                    </div>`;
        }
    }

    customElements.define('test-container', TestContainer);

    promise_test(async function() {
        var root = document.getElementById('shadowHost');
        var shadowElement = root.shadowRoot.querySelector("#shadowScroller");
        document.scrollingElement.scrollBy(0,100);
        shadowElement.scrollBy(0,150);
        await new Promise(resolve => {
            shadowElement.addEventListener("scroll", () => step_timeout(resolve, 0));
        });

        assert_equals(document.scrollingElement.scrollTop, 100);
    }, "Ensure there is no scroll anchoring adjustment in the main frame.");

</script>
